"UDS is over! And in the customary wrap-up I stood up and told the audience what the Foundations team have been discussing all week. One of the items is almost certainly going to get a little bit of publicity. We are going to be doing the work to have btrfs as an installation option, and we have not ruled out making it the default. I do stress the emphasis of that statement, a number of things would have to be true for us to take that decision."

You make it sound as if that's set in stone. Both are FOSS. Grub2 can be modified to understand Btrfs.
The more important question is: Are Canonical for a change willing to do this by themselves?

Given Canonical's track record, I guess they're waiting for Red Hat to do this in time for them (which already doesn't work out for the Nouveau 3D drivers, because Fedora 14 will be released 1 month after Ubuntu 10.10 and adopting a driver that's even beta by Fedora's bleeding edge standards is not something Canonical will do).

That said, I'm hoping that I get positively surprised by Canonical, though my hopes for that aren't high.